Landing with a forefoot strike is best known to reduce knee joint injury, but there’s a trick to it: you must slightly bend your knee when your foot strikes the ground. The slight knee bend at touchdown in running is called knee flexion, and it acts as a cushion, helping to erase high impact forces.
How to Avoid Knee Joint Injury When Running
Bending the knees when forefoot running reduces knee pain injury by improving stride mechanics. For example, bending the knees reduces stride length and increases cadence, which in turn reduces knee joint stress and strain during forefoot running.
- Higher cadence is directly related to less ground contact time, therefore less ground-force production.
- A shorter stride at touchdown allows ankle plantar flexion and a flatter foot strike on the balls of the foot, thereby preventing jarred ground contact.
- A shorter stride length reduces deceleration, which reduces center mass velocity, peak hip adduction angle and moment, and tibial accelerations.
As you can see, bending the knees during forefoot running is exceptionally protective, not only on the knee joint, but on the entire body as well.
How Bending the Knee Protects Knee Joint
Bending the knees when forefoot running protects the knee joint by lowering the ground reaction force, thereby preventing knee pain injury, such as anterior knee pain (Diebal et al.)
In contrast, heel strike runners do not bend their knee at touchdown and land with greater knee extension. However, it is important to bend the knees during running because it helps prevent heel strike by reducing full ankle dorsiflexion at touchdown.
The Take Home Message
If forefoot running feels as if you are pounding the ground, you are probably not bending your knees as much as you should.
Focus on bending the knees at an angle that makes the ground feel soft, even on pavement! Closely evaluate how the ground feels on your legs when experimenting with different knee bend angles.
An important overall conclusion is that bending the knees counteracts the blunt force at touchdown and contributes to mechanical efficiency in forefoot running.
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Gershuni et al. Ankle and knee position as a factor modifying intracompartmental pressure in the human leg. J Bone Joint Surg Am, 1984; 66:1415-20.
Squadrone R and Gallozzi, C. Biomechanical and physiological comparison of barefoot and two shod conditions in experience barefoot runners. J Sports Med Phys Fit, 2009; 49:6-13.
Tsintzas et al. The effect of ankle position on intracompartmental pressures of
the leg. Acta Orthop Traumatol Turc, 2009; 43:42-8.
Winter, DA. Moments of force and mechanical power in jogging. J Biomech, 1983;16:91 e 7.
BSc Neurobiology; MSc Biomechanics candidate, ultra minimalist runner & founder of RunForefoot. I was a heel striker, always injured. I was inspired by the great Tirunesh Dibaba to try forefoot running. Now, I'm injury free. This is why I launched Run Forefoot, to advocate the health & performance benefits of forefoot running and to raise awareness on the dangers of heel striking, because the world needs to know.